Ferruginous bodies: implications in the mechanism of fiber and particle toxicity

Our plain-English summary of Ferruginous bodies: implications in the mechanism of fiber and particle toxicity, by A.J. Ghio, A. Churg, V.L. Roggli (Toxicologic Pathology, 2004).

The study

• Authors: A.J. Ghio, A. Churg, V.L. Roggli
• Journal: Toxicologic Pathology
• Published: 2004;32(6):643-9
• Type of article: Review
• Cited by: 65 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Exposures to fibers and particles can be associated with several different lung injuries including bronchitis, bronchiolitis, pneumonitis, pleuritis, pulmonary alveolar proteinosis, pneumoconiosis, mesotheliomas, and lung cancers. The mechanism of biological effect exerted by fibers and particles has not been exactly defined. Exposures to all fibers and particles introduce a solid-liquid interface into the lower respiratory tract. These surfaces all have some concentration of oxygen-containing functional groups that demonstrate a capacity to coordinate iron. Radical generation is catalyzed by this metal resulting in a cascade of cell signaling, transcription factor activation, and mediator release. We propose that the ferruginous body (i.e., a fiber or particle with a coating of both protein and iron) provides direct evidence of a participation of iron in the biological effect of both fibers and particles. It is recommended that an identification of ferruginous bodies in the lung be regarded as support for a metal-catalyzed oxidative stress in the mechanism of cell and tissue injury.

In plain English

This article was a review, not a new study of patients or workers. The authors drew on published research to explain how inhaled fibers and particles, including asbestos, may injure the lung. A ferruginous body is a fiber or particle coated with protein and iron. The authors described how the surfaces of fibers and particles carry oxygen-containing chemical groups that bind iron. Iron bound this way can drive the production of damaging reactive chemicals, a process called oxidative stress. They argued that the iron in the coating comes from the body, not from the fiber. They also argued that the coating is partly protective: earlier studies they cited found coated fibers less damaging than uncoated ones. They added that much of the iron on the fiber surface is stored in a less reactive form within the iron-storage protein ferritin, but some of it will ultimately be chemically active. Their illustrations included lung tissue taken at autopsy and lungs of guinea pigs and rats given crocidolite asbestos, coal dust, diesel particles or oxalate. The authors concluded that finding ferruginous bodies in the lung should be regarded as support for iron-driven oxidative stress as a cause of cell and tissue injury.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Review (narrative review and proposed mechanism; no new study population)
• Who was studied: No study population. The review was illustrated with human lung specimens taken at autopsy and with lung specimens from guinea pigs and rats given fibers or particles. The number of specimens is not given.
• Exposure: Fibers and particles in general, including asbestos (crocidolite in the animal illustrations), silica and silicates, coal dust, diesel particles, air pollution particles, wood fragments from a fire, carbonaceous fibers and, in rats, oxalate
• Main results:
  • The authors stated that the surfaces of all fibers and particles carry oxygen-containing chemical groups that can bind iron, and that this iron drives the production of reactive chemicals called radicals.
  • The authors argued that the iron in a ferruginous body's coating comes from the body's own iron, not from the fiber or particle.
  • Citing earlier studies, the authors reported that coated fibers (ferruginous bodies) caused less cell damage and less injury than uncoated fibers.
  • The authors argued that much of the iron bound to the fiber surface will be stored in a less reactive form within ferritin, but some portion of this iron will ultimately be chemically active and able to cause oxidative stress.
  • In the illustrations, ferritin (an iron-storage protein) stained along the fiber and in nearby lung cells of an animal exposed to crocidolite asbestos.
  • The authors proposed that the beaded look of some ferruginous bodies arises because iron and proteins collect on the parts of the fiber surface that carry silanol groups.
• The authors' conclusion: The authors concluded that finding ferruginous bodies in the lung should be regarded as support for iron-driven (metal-catalyzed) oxidative stress as the mechanism of cell and tissue injury.

Topics

Medical terms in this study, explained in our Lexicon: Ferruginous body, Pneumonitis, Pneumoconiosis, Mesothelioma, Lung Cancer, Oxidative Stress.

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